Mental health disorders affect many people around the world. Among such disorders, dementia is particularly common among the elderly. According to recent statistics, 800,000 people in the UK alone (according to the Alzheimer's Society) and 36 million worldwide (according to the World Health Organisation) currently have dementia, with the numbers doubling every 20 years. One in three people over the age of 65 will end their lives with dementia. 46% of people with dementia living in the UK never receive a diagnosis. National Health Service memory clinic waiting lists in the UK average six months (up to 18 months), and undergoing the full diagnostic process within the clinic usually takes another six months. Thus, to alleviate the burden and reduce the waiting lists for such clinics, there is a desire to be able to diagnose dementia quickly and easily.
Furthermore, brain changes underlying Alzheimer's disease develop over a period of at least 20-30 years prior to the onset of symptoms. The diagnosis is often not made at all, or made very late in the process, by which time cognitive impairment, disability and behavioural symptoms may be all quite marked. There is therefore a desire to advance the time at which diagnosis can be made. Through doing so, it is hoped that future treatments could then target the disease in its earliest stages, before irreversible brain damage or mental decline has occurred.
Moreover, the impact of a dementia diagnosis depends greatly upon how it is made and imparted. Evidence suggests that when people with dementia and their families are well prepared and supported, initial feelings of shock, anger and grief are balanced by a sense of reassurance and empowerment. Thus, early diagnosis of dementia is desirable, to allow people with dementia to plan ahead while they still have the capacity to make important decisions about their future care. In addition, they and their families will be able to receive timely practical information, advice and support. Only through receiving a diagnosis are they able to get access to available drug and non-drug therapies that may improve their cognition and enhance their quality of life. And they can, if they choose, participate in research for the benefit of future generations.
In the UK the lead specialty that has evolved to diagnose and treat people with dementia is old age psychiatry. However, diagnosis and treatment might also be carried out by a geriatrician (e.g. if there is concomitant acute physical illness requiring admission to a general hospital), a neurologist, adult psychiatrist, liaison psychiatrist, neuropsychiatrist (e.g. where the person is relatively young) or a GP (where the GP has a particular skill or interest in the area). Although families provide the majority of care received by people with dementia, professional health care can be vital to the individual with dementia and their family. A lack of diagnosis means a lack of specific treatment and care for dementia. Diagnosis is the gateway for care.
Dementia is conventionally diagnosed when progressive cognitive decline has occurred, and this has had a noticeable impact upon a person's ability to carry out important everyday activities. It is a clinical diagnosis, supported by careful neuropsychological testing, a history from the patient (subjective impairment in memory and other cognitive functions) and from a key informant (objective signs suggestive of cognitive decline, and evidence of impact on social and/or occupational functioning). Neuroimaging is used, where available, to exclude other organic causes of cognitive impairment, and to provide information supporting definition of subtype. Other tests may be done to rule out other causes of cognitive changes such as thyroid disease, vitamin deficiencies or infection.
However, even with advanced existing techniques, dementia diagnosis rates are very low. Of the 800,000 people living with dementia in the UK, less than half have received diagnosis. Without diagnosis patients are denied access to support, information and potential treatments that can help them to live well, and as their condition develops it is likely to become more costly for the health service to treat. It is also shown that the rate of diagnosis varies dramatically from one geographical location to another (35% in Southwest England, to over 70% in parts of Scotland and Northern Ireland). This further highlights the inefficiencies in the existing diagnosis process.
Likewise, in the US, dementia is the sixth most common cause of death, costing the economy US$216 billion in 2012. By 2019, more than 100 million Americans will be over age 50. Roughly 1 in 8 will develop dementia over age 65 (Alzheimer's Association 2012). Despite the common myth that nothing can be done for affected patients, it is now proven that the disease symptoms can be delayed for years if the medication is started prior to the progressive phase. Also, latest studies show that the disease possibly could be cured if diagnosed at an early stage of development known as mild cognitive impairment (MCI).
More than five million Americans currently have Alzheimer's disease. By 2050, nearly 14 million (13.8 million) Americans could be living with the disease, unless scientists develop new approaches to prevent or cure it.
Worldwide, nearly 36 million people are believed to be living with Alzheimer's disease or other dementias. By 2030, if breakthroughs are not discovered, we will see an increase to nearly 66 million. By 2050, rates could exceed 115 million.
Total payments for health care, long-term care, and hospice care for people with Alzheimer's disease and other dementias are projected to increase from US$200 billion in 2012 to US$1.1 trillion in 2050 (in 2012 dollars). This dramatic rise includes a six-fold increase in government spending and a five-fold increase in out-of-pocket spending.
People who have Alzheimer's disease need others to care for them, and many of those providing care are not paid for their time and services. For example, more than 15 million Americans provide unpaid care for someone with Alzheimer's disease or dementia. Unpaid caregivers are usually immediate family members or other relatives and friends. In 2011, these people provided an estimated 17.4 billion hours of unpaid care, a contribution valued at more than US$210 billion.
The bulk of the publications in this field focus on memory tests. Some attempts have been made to look at response times. For example, WO02078536A1 looks at response time tests on visual images for AD and other conditions. US2002072859A1 relates to a test for the onset of dementia using visual images. It also mentions fatigue. WO2004060164A1 discloses a test including a test stimulus, masking, user response; perception of characteristic and response time. Data is first built up on a user through repetition and then a determination of cognitive impairment is made.
Thus, in view of the above issues, the present work seeks to provide a way of obtaining early detection of dementia. Surprisingly, we have found that the use of natural images allows for early detection of dementia, prior to onset of memory-loss symptoms.